The most common and most likely answer to this crossword clue is the 8 letter word RINGTONE
R
I
N
G
T
O
N
E
More clues leading to the result RINGTONE
- One’s heard on the phone offering to negotiate, to some extent
- Series of notes seeking an answer?
- Circle character that calls for an answer
- Distinctive sound of mobile Girton ‘fresher’, not old
- Musical cycle has style and contemporary sound
- Mobile resonating as missing such a noise
- Communication signal from character at back of group
- Strain of a phone in liquid nitrogen
- Band with quality sound that’s hard to ignore?
- Nitrogen distorted call signal
Buddy explains!

The straight part
We know that "Distinctive s/ound/ of mobile" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case distinctive s/ound/ of mobile = ringtone.The cryptic/wordplay part
In cryptic crossword there's often an wordplay/cryptic part as well.This part involves a more complex hint, such as an anagram, homophone, hidden word, etc.
Sadly, We don't have an explanation for this specific crossword clue yet.
What does RINGTONE mean?
RINGTONE noun- The sound made by a telephone when ringing.
- A customizable tone used to indicate an incoming call on a telephone, especially a mobile phone.
- Of a telephone: to play a ringtone.